Home automation on personal networks is certainly a large use case for these devices, but I think you underestimate the number of ESP8266/32 devices that are us

Home automation on personal networks is certainly a large use case for these devices, but I think you underestimate the number of ESP8266/32 devices that are used in enterprise environments. The Industrial IoT space is pretty big, using small wifi chips like the ESPs for stuff like factory data collection or data center monitoring. I also have personally seen them used in medical device environments and security systems (think wireless door sensors and the like). The "big boys" probably use custom made silicon (but even then I've seen custom-made silicon with an ESP8266 mounted onto it to abstract out the wifi connection part), but I wouldn't be surprised if the majority of IIoT startups use the ESPs as part of their products.